Turning waste into energy

One of the biggest concerns with converting biomass into usable energy has always been the amount of land and water used to obtain it. Crops grown exclusively for biofuel production are often in competition for land and water use in food and fibre production. To overcome this problem, a second-generation of biofuels made from non-food biomass, such as wood process wastes and rice straw have been developed.

Dr. Jack Saddler, a professor in the University of British Columbia’s (UBC) the Faculty of Forestry presented his research of biofuels at the AAAS’ annual meeting held in Vancouver last week. He has studied converting forestry and agricultural residue such as pulp and corn stover (leaves and stalks) into ethanol [1].

In a recent UBC press release, Dr. Saddler says that with the global demand for energy continuing to grow, the biofuels industry will emerge as an economically and environmentally sustainable solution [2].

Although the global biofuel production in 2008 reached ~83 billion litres, it only represented ~1.5% of the global transport fuel consumption [3]. Biofuel production has been steadily increasing and is projected to grow to 167 billion of litres of gasoline equivalent, or ~4% of the total transport fuel demand, by 2030 [3].

The increased biofuel production will also include a greater contribution of second-generation biofuels. Currently, second-generation biofuels are not widely available commercially. The production is mostly in the demonstration stage [3].  However, Canada’s Dynamotive has established commercial plants which convert organic wastes into bio-oil using a fast pyrolsis process. In 2003, Dynamotive’s West Lorne Plant in Ontario, Canada operated a 100 ton per day commercial plant that was able to generate 2.5MW of electricity to the Ontario Power-grid [4].

The main driving force for second-generation biofuel production is largely from government policies which mandate conventional fuel be blended with a certain volume of biofuels. So far, the United States is the only country to have adopted a blending mandate for second-generation biofuels—the Renewable Fuels Standards (RFS), part of the Energy Independence and Security Act of 2007 [3]. Right now, most of the biofuel used in the United States is ethanol produced from corn [3]. The RFS requires that blending include second-generation biofules based on lignocellulosic feedstock, biomass from woody or fibrous plant material, from 2010 onwards [3].

It is predicted that domestic biofuel production (first and second-generation) in the United States will not be enough to meet the blending requirements of the RFS [3]. The shortage will likely drive production of second-generation biofuels by other countries such as Argentina, Brazil, China, Colombia, India, Mexico, and those in the Caribbean Basin Initiative, and allow them to become suppliers.

Another driving force for the production of second-generation biofuels is that it can be made from a variety of sources, depending on a country’s resource. For example, Vietnam is an agricultural country with rice straw making up ~66% of the total agricultural waste [5]. Using rice straw, researchers there developed a method for producing bio-oil, a liquid product made from pyrolysis [5]. Pyrolysis is the conversion of solid biomass in a liquid fuel by heat in the absence of oxygen.

The researchers were able to run their pyrolysis process at 450˚C, where conventional pyrolysis processes operate between 500-700˚C, by using a nanoporous catalyst (Al-SBA-15) [5]. A similar bio-oil yield (44-48%) was achieved using a catalyst at 450˚C, compared to operating without at catalyst at 550˚C [5]. It has been reported that pyrolysis can produce up to 75% yield, depending on the specifics of the process [8].

Running the pyrolysis process at a lower temperature (450˚C) reduces the energy consumption needed to process biomass into a useful form or fuel. Over the past 20-30 years, the biofuels industry has been devoting more research and development of second-generation biofuels. The commercialization of it will surely make biofuels an even more viable form of renewable energy.

——–

[1] Farpoint–Faculty profile, (n.d.). Retrieved February 21, 2012 from http://farpoint.forestry.ubc.ca/FP/search/Faculty_View.aspx?FAC_ID=2

[2] The University of British Columbia. (2012, February 17) Retrieved February 21, 2012 from http://www.publicaffairs.ubc.ca/2012/02/17/taking-biofuel-from-forest-to-highway/

[3] OECD/IEA. (2010). Sustainable Production of Second-Generation biofuels [Information Paper].

[4] Dynamotive Energy Systems Corporation. (2011) Retrieved February  21, 2012 from http://www.dynamotive.com/about/corporate-history/

[5] Dang, T., Le, G., Giang Pham, T., Nguyen, T., Dao, D., Hong Vu, T., Thuy Hoang, T., Hoa Tran, T., & Vu, A. (2011). Synthesis of advanced materials for bio-oil production from rice straw by pyrolysis Advances in Natural Sciences: Nanoscience and Nanotechnology, 2 (4) DOI: 10.1088/2043-6262/2/4/045012

[6] Bain, R. L. (2004, August 3-4). An Introduction to Biomass Thermochemical Conversion. Retrieved February 21, 2012, from http://www.nrel.gov/docs/gen/fy04/36831e.pdf

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